Track the glVertexAttribPointer and only update it if it's changed

This removes a lot of unnecessary GL state changes resulting in an
18% performance boost on desktop and 5% on SGX for the 25920 3x3
solid rectangle test case.

Reviewed-By: Samuel

1 files changed, 20 insertions, 0 deletions

diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
index eaae187..f745196 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
@@ -196,6 +196,9 @@ public:
     void drawPixmaps(const QDrawPixmaps::Data *drawingData, int dataCount, const QPixmap &pixmap, QDrawPixmaps::DrawingHints hints);
     void drawCachedGlyphs(const QPointF &p, QFontEngineGlyphCache::Type glyphType, const QTextItemInt &ti);
 
+    // Calls glVertexAttributePointer if the pointer has changed
+    inline void setVertexAttributePointer(unsigned int arrayIndex, const GLfloat *pointer);
+
     // draws whatever is in the vertex array:
     void drawVertexArrays(const float *data, int *stops, int stopCount, GLenum primitive);
     void drawVertexArrays(QGL2PEXVertexArray &vertexArray, GLenum primitive) {
@@ -230,6 +233,7 @@ public:
     void regenerateClip();
     void systemStateChanged();
 
+
     static QGLEngineShaderManager* shaderManagerForEngine(QGL2PaintEngineEx *engine) { return engine->d_func()->shaderManager; }
     static QGL2PaintEngineExPrivate *getData(QGL2PaintEngineEx *engine) { return engine->d_func(); }
     static void cleanupVectorPath(QPaintEngineEx *engine, void *data);
@@ -291,8 +295,24 @@ public:
 
     QSet<QVectorPath::CacheEntry *> pathCaches;
     QVector<GLuint> unusedVBOSToClean;
+
+    const GLfloat *vertexAttribPointers[3];
 };
 
+
+void QGL2PaintEngineExPrivate::setVertexAttributePointer(unsigned int arrayIndex, const GLfloat *pointer)
+{
+    Q_ASSERT(arrayIndex < 3);
+    if (pointer == vertexAttribPointers[arrayIndex])
+        return;
+
+    vertexAttribPointers[arrayIndex] = pointer;
+    if (arrayIndex == QT_OPACITY_ATTR)
+        glVertexAttribPointer(arrayIndex, 1, GL_FLOAT, GL_FALSE, 0, pointer);
+    else
+        glVertexAttribPointer(arrayIndex, 2, GL_FLOAT, GL_FALSE, 0, pointer);
+}
+
 QT_END_NAMESPACE
 
 #endif